Toshiba Satellite S855-S5378 won't boot from CD/DVD or USB

This is actually because of a BIOS setting.  Start the computer and press F2.

Navigate to Advanced

Go down to System Configuration and press enter

You will see something called Boot Mode.  It is probably set to UEFI Boot.  Select and Press Enter.

Choose CSM Boot.

Press ESC and then Exit with saving changes. You computer should now boot again from the Disc/USB.

When done you must set it back to UEFI or Windows 8 will not boot.

Source: Link

DFI LanParty 865PE Post Lights

4 LEDs on = Power applied, checking CPU
3 LEDs on = CPU has been detected OK, checking RAM
2 LEDs on = RAM has been detected OK, checking VGA
1 LED on = VGA has been detected OK, entering BIOS
0 LEDs on = System has booted to the Operating System.

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